public GGenerateResult Generate(BigInteger p, BigInteger q, DomainSeed seed = null, BitString index = null)
{
// 1
if (index.BitLength != 8)
{
return(new GGenerateResult("Invalid index"));
}
// 3
var e = (p - 1) / q;
// 4
var count = 0;
BigInteger g;
do
{
// 5
count++;
// 6
if (count == 0)
{
return(new GGenerateResult("Invalid count"));
}
// Need to make sure the BigInteger conversion doesn't drop leading 00 bytes, always have as much seed as q
var seedBits = new BitString(seed.GetFullSeed()).PadToModulusMsb(32);
// 7
var countBS = new BitString(count, 16, false); // value must be 16 bits long
var U = BitString.ConcatenateBits(seedBits, _ggen);
U = BitString.ConcatenateBits(U, index);
U = BitString.ConcatenateBits(U, countBS);
// 8, 9
var W = _sha.HashMessage(U).ToBigInteger();
g = BigInteger.ModPow(W, e, p);
// 10
} while (g < 2);
// 11
return(new GGenerateResult(g));
}
public GValidateResult Validate(BigInteger p, BigInteger q, BigInteger g, DomainSeed seed = null, BitString index = null)
{
// 1
if (index.BitLength != 8)
{
return(new GValidateResult("Invalid index"));
}
// 2
if (2 > g || g > p - 1)
{
return(new GValidateResult("Invalid generator value, out of range"));
}
// 3
if (BigInteger.ModPow(g, q, p) != 1)
{
return(new GValidateResult("Invalid generator value, g^q % p != 1"));
}
// 5
var e = (p - 1) / q;
// 6
var count = 0;
BigInteger computed_g;
// 7
do
{
count++;
// 8
if (count == 0)
{
return(new GValidateResult("Too many iterations to find g"));
}
// Need to make sure the BigInteger conversion doesn't drop leading 00 bytes, always have as much seed as q
var seedBits = new BitString(seed.GetFullSeed()).PadToModulusMsb(32);
// 9
var countBS = new BitString(count, 16, false); // value must be 16 bits long
var U = BitString.ConcatenateBits(seedBits, _ggen);
U = BitString.ConcatenateBits(U, index);
U = BitString.ConcatenateBits(U, countBS);
// 10
var W = _sha.HashMessage(U).ToBigInteger();
// 11
computed_g = BigInteger.ModPow(W, e, p);
//12
} while (computed_g < 2);
// 13
if (computed_g != g)
{
return(new GValidateResult("Incorrect g value obtained"));
}
return(new GValidateResult());
}